Pressure-gage.



P. SWENSUN.

PRESSURE GAGE.

(Application filed Jan. 25, 1899.)

No. 635,523. Patented Oct. 24, I899.

(No Model.)

THE NORRIS PETERS c0. FHOTO-LIYHO.. WASHINGTON. n. c.

NITED STATES PAUL SVVENSON, OF MINNEAPOLIS, MINNESOTA.

PRESSURE-GAG E.

SPECIFICATION forming part of Letters Patent No. 635,523, dated October 24, 1899.

Application filed January 25, 1899. Serial No. 703,397. (No model.)

To all whom it may concern.-

Be it known that I, PAUL SWENSON, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful Improvementsin Pressure-Gages; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My present invention relates to pressuregages, and is especially adapted for use in connection with steam-boilers.

The invention has for its object to improve the construction of such pressure-gages in the several particulars hereinafter noted; and it consists of the novel devices and combinations of devices hereinafter described, and defined in the claim.

The preferred form of the invention is illustrated in the accompanying drawings,wherein like characters indicate like parts throughout the several views.

Figure 1 is a view, principally in side elevation, but with some parts shown in diagram, showing myimproved pressure-gage with certain appurtenances thereto, the said device being shown as connected to a steam-boiler. Fig. 2 shows the body or stack of the gage with the pressure indicated and certain other parts removed; and Fig. 3 is a'view corresponding to Fig. 2, but illustrating a slightlymodified construction.

Numeral 1 indicates in diagram the outline of an ordinary engine-boiler, and 2 indicates several of the uppermost fines thereof.

In the particular illustration given, 3 indicates a short pipe-section that opens from the boiler 1 below its lowest water-level, and 4 indicates a similar pipe-section which opens from said boiler above its highest water-level. The pipe-sections 3 and 4 lead directly to elbows or valve-castings 5 and 6, that are provided, respectively, with hand-valves 7 and 8. Again, a vertical pipe 9 leads upward from the valve-casting 5, and a horizontally-extended pipe-section 10, having a downturned outer end 11, leads from the valve-casting 6. These details of course are simply incidental to my present invention. It may be remarked, however, that it is of importance in connection with my said invention, which is to be immediately described, that some sort of con nections be provided, the one leading thereto from the boiler from a point below and the other from a point above the water-level there of. The normal level of the water contained within the boiler 1 is indicated bythe dotted line 2'. In this preferred construction of my invention the body of the stack is in the form of a vertically-disposed primary tube or cylinder a, into the upper and lower ends, re-' spectively, of which the pipe-sections 11 and 9 open and are secured so as to form a support for the gage, as well as to convey the fluids thereto. From the side and lower portion of the primary tube a an upwardly-extended secondary tube or branch section a opens. As shown, the tubular sections a and a are cast integral, and it will be noted that the upper end of the tube a is laterally offset, as shown at a so as to give access to the upper end of the lower section of said tube a. The opening at the offset of said tube a is normally closed with a steam and water tight joint by a screw threaded plug a A pressure-indicator of any well-known or suitable form is connected to the upper end a of the tubular branch a"; As shown, this pressure-indicator (marked 1)) is directly connected with the said upper end section a by a stub pipe-section b. As shown and preferred, the tubular body-section Cl, is provided with a pair of testing-cocks f and f, which open therefrom, the former from below and the latter from above the water-level In connect-ion with the body-tube a there may be and preferably is provided a transparent water-tube g of the ordinary construction. This water-tube g is of course in communication at its upper and lower ends with the body-tube a. As shown, valves g control the passages between the tube g and the body tube a.

The construction illustrated in Fig. 3 is identical with that above described, with the single exception thatthe screw-threaded plug a is provided with a depending stem a that terminates at its lower end in a spiral or screw threaded section a the purpose of which will appear later on in the description of the operation.

Operation: The operation of the pressure gage above described will be substantially IOO as follows: Assuming the water-level to be as indicated by the dotted line a in Fig. 1, the column of water in the body-tube a will be on the same leve1-to wit, on a line between the cooks f and f. As the pressures are equal on top of the columns of water in the boiler and in the body-tube a, the levels of the water in these two parts will always be at the same altitude; but this is not true of the column of water in the indicator or branch tube a. On the contrary, as the pressure in the boiler and in the body-tube a increases the column of water in said branch tube will be forced higher and higher in proportion to the pressure, and this increasing pressure will be indicated by the pointer of the indicator 1). From the above statements of the operation it is evident that steam is never allowed to come into contact with the mechanism of the indicator Z) and that the water forced into the branch tube a acts as an intermediate fluidpiston between the live steam and the said actuating mechanism of the indicator. The importance of this construction will be better understood after a few statements have been made as to the objections to the direct application of the steam to the indicator mechanism. As is well known to all persons familiar with this subject, the actuating 1n echanism of these indicators involves delicate spring devices. It has been found in practice that the intense heat produced on these springs by the direct application of live steam will in time draw their temper, and thus weaken the same, with the result that the indicator is rendered inaccurate. With highpressure boilers this detrimental action of the direct steam is of course more serious than with low-pressure steam. Furthermore, in the direct application of steam to the indicator the condensation of steam is liable to form water-plugs, and thus to disturb the actions of the indicator.

By my invention, wherein the water instead of the steam is caused to directly actuate the indicator mechanism, the above objections are removed. As is well known,water is a much slower conductor of heat than steam and is of course always at a lower temperature than the steam. Furthermore, the heat of the water in the tube a, and, in fact, also in the tube a, is rapidly radiated, so that it will always be at a very much lower temperature than the steam. The delicate spring devices are thus insulated, as it were, from the higher temperature of the steam, so that they will not be subjected to heat high enough in temperature to draw their temper or change their normal spring graduations.

In practical experience I have found that indicators of very cheap construction will operate accurately and will be durable when used in connection with my invention.

The purpose of the screw-threaded section a in the construction illustrated in Fig. 3 is to form a retarder for preventing the rapid descent or ascent of the column of water through the branch at, and thus to prevent sudden vibrations of the indicator-pointer.

W'hat I claim, and desire to secure by Letters Patent of the United States, is as follows:

In a pressure-gage, the combination with a primary passage adapted for connection to a boiler, of a secondary or branch passage, opening from said primary passage, the contracted spiral passage constituting a fiuidretarder within said secondary passage, and a pressure-indicator opening to'the upper portion of said secondary passage, substantially as and for the purposes set forth.

In testimony whereof I affix my signature in presence of two witnesses.

PAUL SVVENSON.

"Witnesses:

JAS. F. WILLIAMsoN, F. D. MERCHANT. 

